This invention relates generally to means for coupling machinery components together, and more specifically pertains to an improved torque limiting clutch that interconnects principally between the speed reducer and machinery it operates in order that operational power to machinery can be curtailed upon encountering excessive impeding forces that exceed the acceptable clutch designed torque.
There are a great variety of torque governing couplings available in the prior art, with most of the couplings for use in conjunction with the operations of a motor, or its speed reducer, and interconnecting within the main drive shaft for affording a disconnection or shut-off of the prime mover when excessive torques are encountered by the driven machinery during operation. Essentially, such torque limiting couplings are designed for the purpose of preventing excessive damage to machinery when torque forces are encountered that exceed predetermined levels, such as when tool binding, or the like, may occur at the situs where a machine tool function is being performed. The damages encountered when such adverse conditions prevail are well known in the industry, and can lead to tool damage, or even motor burn-out, in the event that machinery is not shut-off when a machine tool mechanical disruption occurs.
Most of the safety devices associated with torque limiting mechanisms have been designed in the category of mechanically actuated tripping means, and such can be seen in the Schultz U.S. Pat. No. 2,771,171, and which principally incorporates the use of magnetic pole pieces as the means for determining the range of torque that can be tolerated, but which when exceeded, effects the coupler's breakdown.
A variety of other magnetic coupling devices, and principally for preventing overloading of machinery during routine usage, is shown in the earlier Cowell U.S. Pat. No. 3,221,389, in addition to the Gollos U.S. Pat. No. 3,339,819. Further types of magnetic torque limiting devices, and specifically for use in low force operating mechanisms, can be seen in the two United States patents to Tiffany, U.S. Pat. No. 1,136,739, and Cornwell, U.S. Pat. No. 2,300,778.
The combination of magnetic couplers incorporating spring biasing means for gauging torque forces is shown in the earlier patent to Allen, U.S. Pat. No. 3,053,365, in addition to other forms of disconnectors as shown in the United States patents to Wolley, U.S. Pat. No. 3,277,669; Hornschuch, et al., U.S. Pat. No. 3,159,725; U.S. patent to the Spodig, U.S. Pat. No. 2,943,216; the U.S. patent to Beeston, Jr., U.S. Pat. No. 2,885,873; and finally, the United States patent to Hoad, U.S. Pat. No. 2,746,691, and which utilizes a frictional connection between magnetic pieces for determining the degree of torque necessary to effect discoupling through its force limiting device.
Various ball detent couplers that are available in the art, are shown in the U.S. Pat. Nos. 3,701,404; 3,680,673; 3,893,553; 3,981,382; 3,979,925; 3,942,238; 3,927,537; 3,930,382; and 3,866,728.
Other mechanical type of torque limiting couplers. and which incorporate spring biasing means that operate in conjunction with coupling balls, are shown in the United States patent to Steinhagen, U.S. Pat. No. 3,774,837, in addition to the early patent to Bassakos, U.S. Pat. No. 1,883,164. In addition, another patent to Steinhagen, U.S. Pat. No. 3,722,644, discloses the adjustment of torque forces within a coupler through the use of balls held into position by means of spring means. The patent to Ely, U.S. Pat. No. 541,489, discloses another power transmitting mechanism, while a torque release drive coupling means is shown in the United States patent to Vuceta, U.S. Pat. No. 4,006,608. Other United States patents disclosing other variations upon slipping clutch means are shown in the patent to Barnes, U.S. Pat. No. 2,818,712; the patent to Landrum, U.S. Pat. No. 3,050,965; the United States patent to Leonard, U.S. Pat. No. 3,942,337; the patent to Maisch, U.S. Pat. No. 1,566,553; and the patent to Root, et al., U.S. Pat. No. 4,046,237.
One of the early versions of the current invention is shown in the United States patent to Woltjen, U.S. Pat. No. 4,174,621, from which this current invention derives, and which is owned by a common assignee, and discloses means for regulating the positioning of bearings between driving and driven shafts in order to effect machinery disconnection in the event that adverse conditions are encountered.
Finally, various manufacturers have been marketing their own particular style of overload tripping devices, or what are generally categorically defined as release clutches, and such are distributed by companies such as Centric Clutch Company, of Woodbridge, New Jersey, Stearns Electric Division of FMC Corporation, Milwaukee, Wisconsin, by the Browning Division of Emerson Electric Company, in St. Louis, Mo., and the David Brown Sadi S.A., of Brussels Belgium, in addition to the Fail-Safe Overload Device manufactured by Livernois Automation Company, of Dearborn, Mich. The latter device is significant in showing the positioning of steel balls within the transmission system, with said balls being held in position by means of resettable springs, to assure some degree of control over the amount of overload required for effecting mechanical disengagement when excessive torque is encountered.
The invention described in the torque limiting overload coupling application set forth in the cross reference to a related application generally depicts a structured arrangement for suspending detent balls, only on one circumferential half of the same, within both the driving and driven means of the coupling, but also provides a disclosure of structure that is applicable and useful in the formation of the improved torque limiting clutch of this invention. For example, the concept of staggering the detent means in their seating relationship upon the rotatable member, of this current invention, is shown in said copending application, with the advantage being that inherent single positioning features are attained in the relationship between the driving means and the driven means during clutch disconnection, so that the detent means do not constantly encounter and impact against adjacent bearing seats as disconnection occurs, or while some relative rotation may happen between these two components. But, in addition, and as explained in said earlier application, the uniform distribution of the detent means and their seating within equi-spaced bearing seats is also analyzed, and is an attribute that may yet be adaptable for use in conjunction with the torque limiting clutch of this current invention.
It is, therefore, the principal object of this invention to provide an improved torque limiting clutch wherein ball detent means are positioned and held between the driving and driven means through uniformity of accurately determined pressure applied to all the positional detent means and thereby assure a finer accuracy in the degree of torque necessary to effect clutch disconnection.
Another object of this invention is to provide a torque limiting clutch which has been improved to assure greater accuracy in its response to torque pressures generated during machinery usage and in which the clutch of this invention is installed.
Still another object of this invention is to provide an improved torque limiting clutch in which its operating components, as adjusted, may be totally encased so as to assure their freedom from contamination and resultant maladjustment such as occurs with other clutches of current design.
Still another object of this invention is to provide a disconnect clutch which readily externally disposes its adjustment means for ease of manipulation by any machine operator, so that the clutch may be promptly reset and function to disconnect at specified torques during machinery usage.
Yet another object of this invention is to provide a torque limiting clutch which may be interconnected between a series of machinery shafts, flanges, and dials.
Another object of this invention is to provide a machinery clutch that may interconnect between the speed reducer and the indexing machinery rendered functional through its prime mover.
Yet another object of this invention is to provide a disconnect clutch wherein its various driving and driven components are conveniently bearing mounted with respect to each other so as to assure their near frictionless relative rotation with respect to each other, but yet assure total and adequate support for its various components as assembled for usage.
Another object of this invention is to furnish a signal or actuator type plate or other means that is responsive to immediate clutch disconnection so that a micro or other switch can be instantaneously actuated for shutting off power when the clutch disconnects.
These and other objects will become more apparent to those skilled in the art upon reviewing the summary of this invention, and upon undertaking a study of the description of its preferred embodiment, in view of the drawing.